Event Description

Abstract: What are the mental processes that underpin the pathogenesis of psychotic symptoms? In this talk I will focus on three relevant processes that have been proposed to lead, when dysfunctional, to psychosis: learning, probabilistic reasoning and predictive coding. I will describe recent fMRI studies demonstrating abnormal cortical and subcortical brain activation in psychosis during reinforcement learning. I will introduce the concepts of prediction error, and precision-weighted prediction error, and show recent evidence from my group that precision-weighted prediction error signals are encoded in the human brain, are associated with improved learning, are modulated by dopamine, are abnormal in psychosis, and predict psychotic symptoms in patients and schizotypal traits in health. I will describe studies investigating the role of information sampling in probabilistic reasoning, and discuss the role of generalised cognitive impairment or specific cognitive deficits (in evaluating the cost of information sampling) underpinning the “jumping to conclusions” bias in schizophrenia. I will then address predictive coding in psychosis, and how alterations in the balance between prior expectations and sensory evidence may account for faulty perceptions and inferences leading to psychosis. I will discuss changes in how cognitive and perceptual priors influence decision making during the emergence of psychosis. I will close by considering how mechanistic studies of the cognitive pathophysiology of psychosis are relevant for treatment development.